Hydraulic jack



2 Sheets-Sheet l Dec. 269 E93, B. H, ss-MNN HYDRAULIC JACK Filed July 2, 1929 @www RWM

I 2 Sheets-Sheet 2 Bee, 26g H. SHINN HYDRAULIC JACK Filed July 2. 1929 g r1/vanto@ l (ICCO/z m11 Patented Dec. 26, 1933 l UNITED STATES 1,940,821 v HYDRAULIC JACK Byron H. Shinn, Washington, Pa., assignor to Shinn Devices Corporation, Washington, Pa., a corporation of Delaware Application July 2, 1929. Serial No. 375,534

n18 Claims. (Cl.`138-9) This invention is a hydraulic jack, which develops a low pressure during the initial movement of the jack while the load is light, and a high pressure for intensifying the push or lift, of the jack when the load is heavy, andis related to my copending applications Ser. No. 355,852, Ser. No. 420,756, and Ser. No.v 453,072.

With a hydraulic jack, the first part of the movement, where the head or ram is moving up .10 to the load, may be accomplished by relatively low pressure. It is desirable in order to save time to have this initial movement take place quickly. Then it is equally desirable, when the jack takes hold of its load, to -intensify its action 1'5 by bringing into action a high pressure producing means. This is accomplished by this invention. More specifically, the invention comprises a high pressure producing means,l a low pressure producing means and an automatic valve mechanism for shutting olf the low pressure ilid, and for bringing into action the high pressure fluid,

when a certain predetermined pressure has been reached in the system, this predetermined pressure of course being built up rapidly when the ram or head of the jack begins to take hold of its load. 'Ihe jack of this invention moves the ram or head up to the load relatively quicklyA with the low pressure means, and then lifts the load with the high pressure means.

The pressure responsive valve mechanism mentioned above is an important feature of thisinvention, and comprises a valve casing which has in it a valve controlling the high pressure iiuid,

a second valve controllingthe low pressure uid,

. and an actuating device controlling the position of both valves so that when one is open the other is closed, and vice versa. The actuating element just described which controls the valves ris a pressure responsive element, responsive to the pressure in the system, so that when the pressure in the system is below a certain predetermined value the low pressure valve is open while the high pressure valve is closed, but when the pressure in the system exceeds a certain predeterminedvalue, the low pressurevalve is closed and the high pressure valve is opened.

Another feature [of the invention is a uid reservoir for supplying fluid to the actuating cylinders, the reservoir being provided with a weighted, gravity-actuated or spring-pressed follower, acting on the upper surface of the fiuid in the reservoir for maintaining a certain pressure on the surface of the fluid and thereby maintaining a suitable pressure head on the pipes leading'to Y the actuating cylinders.

Another feature of the invention is a pusher element actuated by the piston of the power cylinder, this pusher element having an inclined cam face which bears against a suitable bearing point on the pusher arm of the jack for lifting it. This pusher arm may be pivoted at its lower end and the power applied intermediate its ends, thereby forming a, lever of the second class.

The invention also resides in further details of construction and operation which will be explained in connection with the accompanying drawings illustrating preferred ways of carrying out the invention'. 'f

In these drawings: f

Figure 1 is a vertical 'side view, partly in sec- 70 tion, showing thel preferred form of the invention.

Figure 2"is an enlarged sectional view through the valve mechanism.

Figure 3 is a section taken on the line 3--3 of 75 Figure 1. u

Figure 4 is a sectional view of a modified detail of the valve.

Figure 5 is a side view, partly in section, of a modification. 80

Figure 6 is an enlarged sectional view of the valve mechanism used with'the modification, and

Figure 7 is a section on the line 7-7 of Figure 5.

Referring now to thesedrawings in which similar reference characters indicate similar parts, 5 indicates the longitudinally extending frame provided with usual Wheels 6 at each end. The power cylinder 7 contains the power piston 8 and piston rod 9, which is urged to the right by a spring 10 positioned between the guide `11 and the nut 12. The low pressure actuating cylinder 15 con-- tains the large low pressure piston 16 connected to the piston rod' 17 which in turn is connected to the equalizer bar 18.

The high pressue actuating cylinder 19 contains the'small high pressure piston 20 connected to the piston rod 21, in turn connected to the other end of the equalizer bar 18. The equalizer bar 18 has no fixed fulcrum, and is actuated by a rod 22 connected to the conventional manually operated handle 23 which is pivoted at its lower end 24 l on theframe 5. Y y

Fluid from the large cylinder 15 is led by a pipe 25 to the valve casing 26. Fluid fromthe small actuating cylinder is led by the pipe 27 to the other end of the valve casing. Fluid from the valve is led by the pipe 28 to the power cylinder 7.

Referring now more particularly to `Figure 2, 110

the valve mechanism there shown is designed to permit flow of fluid from the low pressure cylinder to the power cylinder as long as the pressure in the system is below a certain predetermined point and then is designed to reverse the position of the valves to shut off the low pressure cylinder and to connect the system with a high pressure cylinder, so that the high pressure cylinder takes the load when the pressure in the system exceeds this predetermined point.

The high pressure valve 30 is seated in the valve seat 31 and when held closed shuts olf the high pressure fluid. The valve includes a downwardly projecting valve stem 32 which engages telescopically with the tubular member 33 which is provided at its lower end with a flange 34 and abutment 35. Positioned between the valve 30 and the ange 34 is a spring 36 normally urging these two members apart. A small hole 37 provides communication between the interior of 33 and the exterior.

The low pressure valve 40 is similarly constructed, this valve seating in the valve seat 41 and having a valve stem 42 engaging telescopi# cally with the tubular member 43, the upper end of which has a flange 44 and abutment 45, a spring 46 being positioned between the valve and this flange for urging these members apart. A hole 47 provides communication into the interior of the cylindrical member.

The valve actuating rod 50 is a short shaft having abutments 51 on opposite sides of the rod, arranged in staggered relationship, and sockets 52 on opposite sides, also in staggered relationship, these abutments and sockets being so arranged that when one abutment is holding the upper valve in closed position the corresponding socket on the other side receives the abutment on the lower part of the other valve for allowing it to open freely.

The rod 50 is controlled by the pressure within the valve casing, being connected to a piston 55 having a seal 56 of leather or the like, the piston Working in a cylinder 57; a spring 58 bears against the outer side of the piston with variable pressure controlled by the screw plug 59.

The operation of the parts thus far described is as follows:

With the valve elements positioned as in Figure 2, the upper valve is closed by reason of the fact that the spring 36 is compressed very tightly, the spring being compressed about up to its limit. There is a small oil plug trapped inside tubular member 33 when the stem 32 gets past hole 37. This aids in holding the valve closed. This locks the small piston 20 against movement, while the lower valve is held closed only by a spring, whereby it acts as a one way check valve allowing fluid to enter from pipe 25. When the handle 23 is actuated, piston 20 being locked by valve 30, the large piston 16 moves, forcing a relatively large volume of oil through 25, through valve 40 and out pipe 28 into the power cylinder 7 to give a relatively fast movement to the piston rod 9. This takes up any slack and as the jack takes hold of itsA load, a back pressure is built up which is transmitted into the interior of the valve casing, which pressure acting on piston 55 will eventually reach a point to overcome spring 58 and will push rod 50 to the right, causing the lowerl abutment 51 to contact with 45 to lock the lower valve firmly against its seat, the abutment moving 43 until it engages the valve 40, and so holds40. At the same time abutment 35 snaps into upper socket 52, thereby releasing the upper high pressure valve.

Since the large piston 16 is now locked by valve 40, the small piston 20 takes up the load and forces fluid at high pressure through the pipe 27 past the valve 30 and out into the system. When the pressure becomes low again, sping 58 moves the parts back into their original positions.

Fluid under pressure is supplied to the high and low pressure actuating cylinders as shown in Figures 1 and 3. A reservoir 60 is provided, and on the upper surface of the liquid in the reservoir is a follower 61 on which is a spring or weight 62 for exerting a pressure against the upper surface of the liquid, thus providing a slight or low constant head. A pipe 63 provided with a check valve 64 leads uid into the high pressure actuating cylinder 19, while a pipe 65 provided with a' check valve 66 leads uid into the lowpressure actuating cylinder 15.

These two inlet pipes open into the actuating cylinders near the left hand ends thereof in a position such that they are still open when the two pistons are in their extreme positions at the left, at the end of the stroke.

If a single movement of the actuating nandle 23 is not sullcient to lift the load the desired amount, the handle 23is brought back for a second pumping stroke, the piston drawing in a fresh supply of oil through the inlet pipes just described, the valves 30 and 40 holding the load. The pumping strokes of the handle 23 are repeated as many times as necessary to raise the load to the desired point. l

For lowering the load there is provided a bypass 70 provided with a valve 71 for by-passing fluid from 28 into the reservoir 60. Opening of the valve 71 will evidently relieve the pressure, the oil going back into the reservoir, while the spring 10 restores piston 8 to its original position.

The lifting arm 75 may be pivoted at its lower end as at 76 and is provided intermediate its ends with a roller 77 to which force is applied as in levers of the third class by engaging the cam face 78 of a pusher member 79 working on rollers 80, the pusher member 79 being actuated by the piston rod 9. Evidently as the rod 9 is moved to the left the cam 78 will raise the lifting arm 75 of the jack. Other forms of lifting arms and actuating elements could be used.

Figure 4 shows a modification of the actuating mechanism for the valve rod 50. The valve rod 85, corresponding to the valve rod 50 of Figure 2, is controlled by a bellows element 86, made of strong flexible material, such as fabricated rubber or metal. Covering the outer surface of the end of the bellows is a plate 87, the rod 85 passing through the end of the bellows and plate 87, and being secured thereto with a fluid tight nut 88 and washer 88. The other end of the bellows is open to the pressure in the valve casing 26. The bellows is in a suitable casing 89. A spring 90 bears against the outer end of the bellows providing a variable pressure thereagainst, which is controlled by the screw plug 91.

Substantially U-shaped metallic members 92, which are circular in shape, are mounted on the bellows at the several apices thereof, in order to provide strengthening and reinforcement at these places. rIrhese rings also serve as bearing surfaces in case of contact with the interior of casing 89.

Referring to the modification in Figures 5 and 6, the power and actuating cylinders are as in sure is reached.

Figure 1 and corresponding parts are similarly numbered. 'Ihe reservoir 60 is here shown provided with a follower 95 urged down by springs 96, the upper ends of which bear against a base 97.

Figure 6 shows a modified form of two-way, pressure-responsive valve, for connecting the low pressure cylinder to the system `at low pressures, and fordisconnecting the low pressure cylinder and connecting the high pressure cylindervwith the system when a certain predetermined pres- The valve casing 100 is provided with an inlet -pipe 101 from the low pressure cylinder 15 and with an inlet pipe 102 from the high pressure cylinder 19. The outlet pipe 103 to the system is provided with a check valve 104. 105 is a valve seat for a valve 106, which moves on a rod 107, carrying a stop 108.v The upper end of rod 107 passes through bushing 109 of piston 110. The

lso

` the valve chamber 100 increases.

upper end of the rod carries a washer 111, against which springs 112 bear on opposite sides thereof.

The piston has a seal or cup 113 and moves in a cylinder 114, against spring l15,.the push of which is adjustable by the screw plug 116. The upward movement of the piston is limited by the abutment 116' carried by 116.

Piston 110 is provided with upper and lower annular grooves 117 and 118, engageable by a spring pressed detent 119, the pressure on which is controlled by the screw plug 120.

The high pressure valve 121 seats against valve seat 122, the valve having a hollow stem 123 which seats in the underside of valve 106. The top end of 123 acts as a valve to prevent fluid leakage past rod 107. The rod 107 passes into the stem 123 and into space 124 therein, the rod terminating in a head 125 adapted to bear against shoulder 126 in the stem 123. A spring 127 is positioned between valves 106 and 121 and is sufficiently strong to hold valve 121 closed against the high pressure uid from 102.

The parts just described operate as follows:

With the parts as shown in Figure 6, valve 121 is held closed by spring 127 which in turn is held by valve 106 and spring 115. Low pressure uid from pipe 101 passes through the valve chamber 100 and out pipe 103 to the power cylinder 7. As the lifting arm 75 takes hold of its load the pressure in When the pressure has reached a point sufficient to overcome spring 115 and to overcome the holding force of detent 119, piston 110 moves upwardly, valve 106 also moving upwardly by push of spring 127, this seating valve 106 and shutting off the low pressure uid from 101. Valve 121 is still held closed by spring 127. This much is accomplished when the lower groove 118 is about half way up to the detent 119. A'Ihis half way movement also is sutilcient to cause head 125 to move up to Aand engage the shoulder 126. As the piston 110 continues upwardly, head 125, engaging with 126, lifts valve 121 off its seat, thereby, allowing the high pressure i'luid to flow into the valve casing. Valve Y 106 is now held rmly against its seat by the high pressure fluid and by the detent 119 now in engagement with the lower groove of piston 110. The parts remain in this position as long as the pressure continues high. When the pressure falls below a certain predetermined point, the spring 115 pushes the piston down and restores the parts to the position shown in Figure 6.

'I'he detent 119 has a certain frictional grip on the piston 110 which may be regulated by making the grooves 117 and 118 of appropriate depth.

The detent 119 also engages with the grooves 117 and 118 so that it tends tov retain the piston 110 in position until a slight excess pressure is built up, whereby. when the detent lets go, this excess pressure moves the piston with a quick snap action to its new position. ,Y

The valves of Figure 2 and Figure 6 function similarly, in that low pressure fluid from the large piston is admitted to the system when the load is light and pressure low, while the valves automatically act, when a predetermined pressure is reached, to shut off the fluid from the large piston and cut in the fluid from the small piston, when the load is greater and consequent higher pressures are present in the system.

While the invention has been described in detail, it should be understood that the invention is .not to be limited to such details, but may be carried out in other ways.

I claizn as my invention:

1. In a hydraulic jack, a high pressure cylinder, a low pressure cylinder, valvebmeans comprising a valve casing, a spring loaded valve controlling communication with the high pressure cylinder, a spring loaded valve controlling communication with the low pressure cylinder, and a pressure controlled element between the two valves for opening and closing them alternately, so that when one valve is closed the other is open.

2. In a hydraulic jack, a high pressure cylinder, a low pressure cylinder, valve means comprising a valve casing, a spring loaded valve controlling communication with the high pressure cylinder, a spring loaded valve controlling communication with the low pressure cylinder, and a pressure controlled element, responsive to the pressure in the casing, and located between the two valves for causing them' to move alternately to open and closed positions, so that when one valve is closed the other is open.

3. In a hydraulic jack, a power cylinder and piston, a pusher bar having an inclined cam fa'ce, a supporting bed plate therefor, anti-friction rollers for transmitting the thrust from the camLface to the supporting bed plate, a pivoted lifting arm, `and a roller carried by the lifting arm intermediate its ends and bearing on the cam face of the pusher bar.

4. In a hydraulic jack, a low pressure actuating cylinder, a high pressure actuating cylinder, pistons in each cylinder, piston rods for the pistons, an equalizer bar connecting the piston rods, means for applying power to the equalizer bar, a valve means comprising a valve chamber and pressure responsive mechanism in communication with the valve chamber directly operating the valves in response to the pressure in the power cylinder and a single actuating cylinder, for alternately connecting and disconnecting the actuating cylinderswith the power cylinder.

5. In a hydraulic jack, a power cylinder, small and large actuating cylinders, a piston and piston rod for each cylinder, an equalizer bar connected to the piston rods of the two actuating cylinders, means for applying power to the equal- -the power cylinder and a single actuating cylinder, for operatively connecting the large actuating cylinder to the power cylinder at low pressures, and for disconnecting the large cylinder and operatively connecting the .small cylinder with the power cylinder when a predetermined pressure is reached in the system.

6. In a hydraulic jack, a power cylinder, actuating cylinders comprising a high pressure cylinder and a low pressure cylinder, valve means comprising a valve casing, a spring loaded valve controlling communication with thehigh pressure cylinder, a spring loaded valve controlling communication with the low pressure cylinder, and pressure responsive mechanism in communication with the valve chamber directly operating the valves in response to the pressure in the power cylinder and a single actuating cylinder, cooperating with both valves for closing them alternately so that when one valve is closed the other is open. v

7. In a hydraulic jack, a power cylinder, actuating cylinders comprising a high pressure cylinder and a low pressure cylinder, valve means comprising a valve casing, a spring loaded valve controlling communication with the high pressure cylinder, a spring loaded valve controlling communication with the low pressure cylinder, and pressure responsive mechanism in communication with the valve chamber directly operating the valves in response to the pressure in the power cylinder and a single actuating cylinder, cooperating with both valves for closing them alternately so that when one valve is closed the other is open.

8. In a hydraulic jack, a power cylinder, actuating cylinders, valve means including a high pressure valve and a low pressure valve, and pressure responsive mechanism in communication with the valve chamber directly operating the valves in responseto the pressure in the power cylinder and a single actuating cylinder, operatively connected with both valves, for locking one valve closed when the other is open, and vice versa,

9. In a hydraulic jack, a power cylinder, actuating cylinders, valve means including a high pressure valve and a low pressure valve, a common valve chamber for the valves, pressure responsive mechanism in communication with the valve chamber directly operating the valves in response to the pressure in the power cylinder and a single actuating cylinder, connected with both valves for locking one valve closed when the other is open, and vice versa.

10. In a hydraulic jack, a power cylinder, actuating cylinders, valve means including a valve chamber, a high pressure valve and a low pressure valve, and pressure responsive mechanism in communication with the valve chamber directly operating the valves in response to the pressure in the power cylinder and a single actuating cylinder, operatively connected to and controlling the opening and closing of both said valves.

11. In a hydraulic jack, a power cylinder, actuating cylinders, valve means including a valve chamber, a high pressure valve anda low pressure valve, and pressure responsive mechanism in communication with the valve chamber directly operating the valves in response to the pressure in the power cylinder and a single actuating cylinder, connected to both valves for actuating them substantially simultaneously.

12. In a hydraulic jack, a power cylinder, actuating cylinders, valve means including a valve chamber, a high pressure valve and a low pressure valve, and pressure responsive mechanism in communication with the valve chamber directly operating the valves in response to the pressure in the power cylinder and a single actuating cylinder, connected to both valves for opening the one and closing the other substantially simultaneously.

13. In a hydraulic jack, a power cylinder, actuating cylinders, a high pressure valve, a low pressure valve, a common valve chamber for the valves, and pressure responsive mechanism in communication with the valve chamber directly operating the valves in response to the pressure in the power cylinder and a single actuating cylinder, for opening and closing the valves a1- ternately.

14. In a hydraulic jack, a power cylinder, high pressure producing means, a high pressure valve for controlling the flow of uid therefrom, low pressure producing means, a low pressure valve for controlling the flow of uid from the low pressure producing means, a valve chamber, and a common pressure responsive mechanism in communication with the valve chamber directly operating the valves in response to the pressure in the power cylinder and a single pressure producing means, for actuating both said valves.

l5. In a hydraulic jack, a power cylinder, high pressure producing means, a high pressure valve for controlling the flow of uid therefrom, low Y pressure producing means, a low pressure valve for controlling the ilow of fluid from the low pressure producing means, a valve chamber, and common pressure responsive mechanism in communication with the valve chamber directly operating the valves in response to the pressure in the power cylinder and a single pressure producing means, connected to both said valves for permitting only one valve to open at a time, the other valve meanwhile being closed.

16. In a hydraulic jack, low pressure means for moving the jack quickly for a light load, high pressure means for moving the jack more slowly for a heavy load, and pressure actuated mechanical means responsive to the pressure therein and in a single pressure means for bringing one of 'said pressure means into operation and simultaneously positively locking the other against operation.

17. In a hydraulic jack, a power cylinder, high pressure producing means, low pressure producing means, high and low pressure valves for controlling the ow of fluid from the pressure producing means respectively, a valve chamber, pressure responsive mechanism in communication with the valve chamber directly operating. the valves in response to the pressure in the power cylinder and a single pressure producing means for holding one valve closed when the otheris open, and vice versa, a reservoir for supplying fluid to the pressure producing means and a gravity loaded follower in the upper part of the reservoir for maintaining a pressure on the uid therein.

18. A hydraulic jack comprising in combina-` tion, a high pressure cylinder, a low pressure cylinder, a liquid reservoir to supply liquid to the cylinders, a power cylinder actuated by the pressure cylinders and actuating a lifting arm, pressure responsive valve mechanism in communication with the cylinders operable when a limiting pressure within a predetermined range is built up within the'valve mechanism to shut oif the low pressure cylinder with the power cylinder and to connect the high pressure cylinder with the power cylinder, and a by-pass valve for allowing fluid from the power cylinder to flow backinto the reservoir, thereby releasing the load.

BYRON H. SHINN. 

